Happy death day 2u is about Tree Gelbman who survived the time loop that she was stuck in where she was murdered again and again by a sadistic killer. In this sequel we find her stuck in this time loop again. This happens because of Ryan and his sci-fi shenanigans. He's a geeky science student and is working on some project. Tree is now set to fight for her life and stop all this for good. She needs to help Ryan to get to the correct algorithms and when they don't, her cycle resets.